In liquid wells, such as water and oil wells, the well borehole is typically lined with a casing extending at its distal, or downhole, end to a depth into or below the saturated region in the subterranean formation. The distal end of the casing is perforated in order to permit the liquid to flow into the casing and rise to the static liquid level in the subterranean formation. For example, the liquid enters a water well and rises to the static aquifer level. This creates a pooling of the liquid as a liquid column in the casing which can be readily pumped to the surface either by a jet pump at the surface or by a submersible pump within the liquid column.
The liquid flows into the casing through one or more fissures, or veins, in the subterranean formation. The specific capacity of the well is directly related to the fissures' ability to replenish liquid into the casing at a rate equal to or greater than the rate at which the liquid is pumped out of the well. A well with inadequate liquid replenishment can be readily depleted. That is, even under ordinary usage, at best the specific capacity can be adversely affected by the reduced supply head pressure of the liquid column; at worst the liquid column level can drop below a pumpable level.
Drilling a well is a results-oriented endeavor, in that a driller cannot precisely determine the flow rate quality of fissures in the borehole area until functionally testing the completed well. An inadequately performing well might be abandoned and redrilled elsewhere, or might be worked-over to attempt to physically enlarge the fissures at the casing distal end.
However, even an adequately performing well can deteriorate with time to become depleted. Existing fissures can shrink and even close, due to the earth shifting and/or silting in as debris is carried with the liquid. In the event of a well deteriorating to an unusable performance, the well might be similarly abandoned for a new well nearby or it might be worked-over, which are relatively expensive and labor-intensive options.
What is needed is a quick, effective, and relatively inexpensive solution to stimulate an existing liquid well to increase its specific capacity. It is to this solution that the embodiments of the present invention are directed.